It is well known to form corrugated strips for use in various devices such as the fins of heat exchangers by moving a flat strip continuously between forming rolls and thereafter through packing rolls to a cutting position, interrupting the movement momentarily at the cutting station and cutting a predetermined length of web from the strip. If the length of corrugated strip is not precisely controlled, the cutting may occur along portions other than the apices which connect the strip. The resultant edge is flawed, makes it difficult to handle the strip. In addition, such an edge can adversely affect the positioning of the strip in the device in which it is to be used.
The problem of cutting such strips is made more complex because of the differences in characteristics of materials. For example, some materials inherently remain in the formed position while others are readily deformed. This affects the spacing of the number of corrugations in any unit length. Specifically corrugations of copper tend to return to there original configuration and spacing if spread in longitudinal direction of the web. Aluminum, on the other hand, must be handled carefully since it does not tend to return to original configuration and spacing. The problem is further complicated by the fact that the spacing of the corrugations may be such that it is difficult to move a cutter into position for cutting at the apex the corrugation.
In U.S. Pat. No. 5,069,053 issued Dec. 3, 1991, there is disclosed and claimed a method and apparatus for cutting corrugated webs from a strip which is continuously formed to define transverse undulating fins or corrugations comprises periodically interrupting the movement of the corrugated strip, spreading a corrugation in the direction of the longitudinal axis of the strip and severing the corrugation at the spread corrugation and the apex of the corrugation. More specifically, the corrugated strip is interrupted, adjacent corrugations are moved longitudinal relative one another to locate the corrugation to be cut and a cutter is moved between the adjacent apices to cut the connecting oppositely disposed apex In one form adjacent apices are engaged and spread apart. In another form, a finger engages a side of a corrugation to position the corrugation to be cut.
In prior U.S. Pat. Nos. 4,262,568 and 4,507,948 other apparatus and mechanisms are shown for cutting corrugated strips.
Where the corrugated strips includes louvers which extend transversely of the strip, the louvers project into the space through which a saw or a knife blade would move and it has been found that the louvers have a tendency to interengage and the louvers are sometimes severed not only affecting the function of the fins and their ultimate use but, in addition, resulting in fragments of the light strip material being severed and have advertently affecting the functioning of the apparatus as well as contaminating the area of the apparatus.
Among the objectives of the present invention are to provide a method and apparatus for cutting corrugated strips and particularly strips having louvers wherein the louvers are not inadvertently severed; wherein the corrugations are severed accurately along the apex; and wherein the apparatus can be readily adapted to the conventional corrugating apparatus.
In the accordance with the invention, a method and apparatus for cutting corrugated webs having louvers from a strip which is continuously formed to define undulating fins or corrugations extending transversely of the strip. The method and apparatus comprises periodically interrupting the movement of the corrugated strip, locating the strip, and severing the corrugation along an apex by moving a shearing cutting blade such that the blade is moved to engage and cut beginning at one longitudinal edge and progressively across the apex of the corrugation to the other edge of the corrugation. The apparatus functions to lift the knife blade initially to separate the corrugation thereby moving louvers out of contact with one another such that the louvers would not be severed by the movement of the knife blade.